/**
 * 137. 只出现一次的数字 II
 * https://leetcode.cn/problems/single-number-ii/description/
 */
class Solution {
    public int singleNumber(int[] nums) {
        int ret = 0;
        for(int i = 0; i < 32; i++) {
            int sum = 0;
            for(int x : nums) {
                if(((x >> i) & 1) == 1) sum++;
            }
            if(sum % 3 == 1) ret |= 1 << i;
        }
        return ret;
    }
}